"Find the limit: "
Although you are expected to be able to solve such limits "by hand", it can be very useful to use your calculator to check your work and to generate practice problems on your own. Here's how it works:
On the TI89, limits at infinity (or negative infinity) are handled just like other limits. The infinity symbol is entered by pressing <green diamond><CATALOG> 

The screen at right shows the TI89 solution to Example 4b on p. 191 of the Larsen text: 